Question

How are interferometers used to measure electromagnetic waves?

Answer 1

The resolving power of a telescope is limited by its diameter. Making very wide telescopes is extremely expensive. The solution is to use two widely spaced devices and combine the results.

Explanation:

I don’t understand the mathematics (never had to teach it) but the principle is clear. The two (or more) telescopes in the array can function as if they had a diameter equal to their separation so the resolving power, the ability to distinguish two closely spaced objects, rises accordingly.

Amazing, perceptive experimental development!